MXPA98007603A - Transfer label comprising a reinforcement layer and a transfer layer, a container that comprises such a transfer layer and the method to remove a transfer layer from a recipie - Google Patents

Abstract

The present invention relates to a transfer label comprising a reinforcing layer and a transfer layer, which is loosely coupled to the reinforcement layer. Upon transfer to a container, the transfer layer is decoupled from the reinforcement layer. After coupling to a container, the transfer layer can be removed in an aqueous liquid under turbulent soaking conditions at a temperature of not more than 100 ° C, preferably not higher than 70 ° C. During these conditions, the transfer layer is broken into at least four parts, wherein each part is no smaller than 5 microns. The transfer layer is uncoupled from the container within a soaking time of no more than 20 minutes, preferably no more than 10 seconds. The transfer label according to the present invention has a very high adhesion during storage and use conditions, and can be quickly removed from a container, such as a reusable bottle box, in an economical manner.

Description

TRANSFER LABEL THAT COMPRISES A LAYER OF REINFORCEMENT AND A TRANSFER LAYER, RECIPIENT THAT UNDERSTANDS SUCH TRANSFER LAYER AND THE METHOD FOR REMOVE A TRANSFER LAYER FROM A RECIPIENT BACKGROUND OF THE INVENTION The invention relates to a transfer label comprising a reinforcing layer and a layer of. transfer releasably coupled thereto, whose transfer layer can be decoupled from the reinforcement layer for transfer to a container. The invention also relates to a container, in particular to a plastic package, comprising such a transfer layer and to a method for removing such a transfer layer from a container. It is known in the technology of packaging or packaging to label containers such as boxes. or plastic packaging by providing a permanent non-removable image by a silk mesh method. Such labels offer a highly durable finish with availability of two or three colors. This technique nevertheless offers limited colors, lacks the improved graphics that ref. 28453 offer other labeling techniques, is not flexible in its ability to have graphical changes, to meet market strategies leading to large inventories of obsolete units, and tends to show signs of wear and tear after approximately four trips. When the removable inks are going to be applied to the reusable plastic boxes by stencil printing or a tampon printing process, the inks have to be applied in the bottling plant, such as a brewery, which can lead to problems with regarding the registration. After the boxes are removed by means of the box washers, the inks will be dissolved in the washing liquid and in this way contaminate the box washers. In addition, the speed of application is limited, and the curing of the inks requires a lot of space and long storage times before distribution. A second way of labeling the containers involves gluing the printed paper labels to the containers, such as plastic boxes or bottles at the time of filling and sealing. This type of labels nevertheless offers little resistance to label damage from handling and exposure to moisture (wrinkling). In addition, paper labels are difficult to remove from the boxes, and tend to clog the box scrubbers available today. After the removal of the paper labels from the plastic boxes, a residue of glue or glue may be left on the boxes. A third technique for labeling containers, in particular glass bottles, is based on the principles described in International Patent O90 / 05088. In this publication, we describe a method for labeling bottles, which provides a highly impact resistant, durable label, and still allows high definition label printing. A transfer label consisting of a removable reinforcement layer is provided, whose reinforcement layer is reverse printed with an acrylic or vinyl ink, which is cured and overprinted with adhesive. The label is applied to the container with its adhesive surface in contact with it. The reinforcing layer is separated from the label transfer layer, for example by applying heat to either the container, the label or both. The labeled container is then applied with a coating that is subsequently cured. The cured coating provides the required degree of impact resistance and durability. The disadvantage of permanently coupled labels is that when these labels become scratched or otherwise damaged, they can not be easily removed from the bottles. Also, it is not possible to provide the same containers each time with new and / or different labels, which is desirable for promotional activities. An object of the present invention is to provide a transfer label comprising a transfer layer having good adhesion to a container during storage and use, which can be easily removed from the container for the replacement of the label by a new one and / or different labels. A further objective of the present invention is to provide a transfer label with an attractive appearance, which can be printed on a wide variety of designs and colors and which can be removed from the container in an environmentally friendly manner.

A further objective is to provide a system of returnable boxes, which can be provided with attractive labels, which can be easily and economically removed and reapplied. The labels must be applied and removed at relatively high speeds.

BRIEF DESCRIPTION OF THE INVENTION These and other objectives are achieved by the transfer label according to the present invention, which is characterized in that the transfer layer, after coupling to a container and under conditions of turbulent soaking in an aqueous liquid of a temperature no greater than 100 ° C, preferably not greater than 70 ° C, breaks in at least 4 parts, each pair being no smaller than 5 microns and uncoupled from the container within a soaking time of no more than 20 minutes, preferably no more than 20 seconds. Surprisingly, it was found that the advantageous properties of good adhesion of the transfer layer to the container during storage and use, and the easy removal capacity for re-labeling purposes, were provided by the labels which are broken during the solutions of Soak without dissolving in the soaking solution. Without the desire to commit to any theory, the breaking of the transfer layer during removal by soaking is assumed. it provides an increase in the number of label positions where the soaking solution can penetrate and attack the interface of the container and the label, and can therefore uncouple the label from the container. With this, a very quick removal or removal of the container label is achieved at modest temperatures. As the label disintegrates into smaller fragments, these fragments can be removed from the soaking solution by a simple sieving process, without the labels dissolving in the soaking solution. With this does not occur the contamination of the washing solution, and the effluents towards the surroundings, of ink and other parts of the label, can be prevented. During the wet removal process, no more than 10% by weight of the ink in a transfer layer is dissolved in an alkaline wash solution. This prevents the containers from being discolored by the inks. In addition, the ink levels in the wash solution remain low enough not to affect the aerobic and anaerobic treatment in the waste water treatment plants.The low concentrations of inks in the waste water prevent the accumulation of metals in the wastewater. sludge from wastewater treatment plants, so that this sludge will not have to be treated as chemical waste under government regulations.Surprisingly, it was found that the transfer labels that are broken into pieces in the soaking solution according to The present invention can be very quickly removed using conventional box washing apparatus, which is normally used to remove dirty labels and / or paper from reusable plastic boxes to contain bottles. invention can for example be removed from a plastic box within ten (10) seconds os, compared to a time of removal of several minutes or more for conventional paper labels. Still, the adhesion of the transfer label according to the invention to a container, preferably to a reusable plastic box for bottles during conditions in use and its scratch resistance, are very good in comparison to conventional paper labels. Although it is preferred to use the transfer layer according to the present invention on reusable plastic boxes, the label can also be used in combination with plastic bottles, such as PET-type bottles, plastic food trays, glass bottles and the like. . A preferred transfer label according to the present invention comprises a transfer layer which is permeable for soaking liquids. By "permeable" it is understood that a transfer layer has a water collection value after 3 hours between 0.0 and 100 g / m2, preferably of about 5 g / m2, in water at room temperature Such labels have a water vapor transmission rate of between 50 and 750 g / m2, preferably of approximately 600 g / m2 after 24 hours for water at The transfer layer may comprise a cover layer underlying the ink pattern, the cover layer of which forms the surface facing outwards after the coupling of the transfer layer to a container.The cover layer may for example be formed of an acrylic wax coating The cover layer can be a continuous layer, or it can be discontinuous and printed to register with the ink pattern The acrylic wax covering layer can be very advantageously penetrated for example by a 0.5% sodium hydroxide solution, while providing a sufficient barrier to the penetration of moisture during storage and the conditions of use of the label ta on a container. Labels according to the present invention, which combine sufficient durability with rapid and economical removal, have a pencil hardness between IN and 7 N in the dry state and a pencil hardness less than 0.5 N after a soaking time between 1 minute and 15 minutes in water at 20 ° C. In a further embodiment of the transfer label according to the present invention, the ink pattern is discontinuous, such that areas of reduced thickness are formed in the transfer layer. In the washing process, these areas of reduced thickness, for example between separate areas of ink pattern, can form natural lines of weakening, such that the breaking of the label in these areas can more easily occur. The transfer layer preferably comprises an adhesive layer, the tack or adhesion of which is at least reduced by contact with the soaking liquid. According to a preferred embodiment, the adhesive is dissolved by the soaking liquid. Preferably, this adhesive layer is discontinuous and printed to register by the ink pattern. A suitable transfer label has a transfer layer with a thickness of no more than 30 microns, preferably no greater than 20 microns. The weight of the sediment or deposit of the adhesive layer is not greater than 10 g / m2, preferably around 3-6 g / m2. These weights provide good adhesion of the label during use and allow the label to be broken into parts during the washing process. In one embodiment, the labels according to the invention are applied to returnable boxes. The need for returnable boxes is a direct result of industry preference and government legislation regarding returnable (refillable) containers in various parts of the world, rather than one-time packaging. In this type of recycling environment a new complete market has been created for handling packaged beverage containers. This is currently true for glass and PET bottle containers that can be refilled. By using the transfer label according to the present invention, a simple blank box can be used which can be provided in an easy and inexpensive way with an image print that can also be easily removed after the box is Returned to the bottle line to refill. The containers that are provided with a transfer layer according to the present invention can be "cleaned" very quickly in a conventional box washing station with cleaning times per container below 1 minute, preferably below 10 seconds at temperatures below 100 ° C, preferably below 70 ° C. The soaking solution is pumped through a sieve that collects the pieces of the broken labels. The sieves are periodically cleaned and the pieces of labels are removed from the sieves of the washing station. According to a preferred modality, a protective, transparent covering layer is coupled onto the transfer layer on or after the coupling of the transfer layer to the container. This covering layer or coating improves the resistance of the label against environmental influences, without deteriorating its breaking properties during washing conditions. A preferred material for the protective coating is compatible with the material of the ink used in the transfer layer. Most preferably all the materials, the adhesive, the ink and the protective coating are based on acrylate polymers. In order to improve the durability of the label additionally, without deteriorating its breaking properties during the washing conditions, one or more heat treatments may be given after the application of the label, causing a shrinkage of at least some parts of the label. the transfer layer, to provide a coalescence of the materials of the various layers. This results in an improved service life without deteriorating the wash behavior of the transfer layer. The label according to the present invention which combines sufficient durability during storage and use, with rapid and economical removal, has been preferably thermally treated after application to the container, at a temperature between 40 ° C and 100 ° C, preferably between 50 ° C and 90 ° C. By careful selection of the composition to the label, the use of a protective coating and the nature of the post-treatment (heat treatment) it is possible to direct or orient the properties of the transfer layer, especially with respect to the behavior during washing. The selection of the adhesive to be used in the adherence of the image of the label to the surface of the container will influence the cleaning properties. The adhesive must have been activated before or during the application of the transfer layer to the container. An easy and generally preferred method of image application is through the use of heat activatable adhesives, which have been applied to the image in the form of an inverted printed label. Other methods include the use of adhesive that can be activated through radiation, chemicals, electron beam, microwave, UV and the like. It is also possible to use adhesives that can be activated through photoinitiation, moisture, enzymatic action, pree or ultrasound treatment. A preferred adhesive has a low adhesion temperature, preferably between 60 ° C and 90 ° C, more preferably between 80 ° C and 90 ° C. Instead of a separate layer of adhesive, it is also possible to use in the transfer layer an ink which itself has adhesive properties after activation.

BRIEF DESCRIPTION OF THE DRAWINGS The embodiments of a transfer label and a washing method according to the invention will be described hereinafter in detail, with reference to the accompanying drawings. In the drawings: Figure 1 shows a thermal transfer label according to the invention.

Figure 2 shows a washing device for the removal of a transfer layer according to the present invention, from a container, in particular from a plastic box or packaging.

Figure 3 shows a cross-sectional view of the washing device according to Figure 2, along the line III-III.

Figures 4-8 show various embodiments of the transfer layer of a transfer label according to the present invention.

Figure 9 schematically shows a method for applying the transfer layer according to the present invention to a returnable box or package, and Figures 10 and 11 graphically show the removal time of a transfer layer at different thermal post-treatment temperatures, without a wax cover layer and with a wax cover layer, respectively. 1 The preferred embodiment of the label according to the present invention will be described first with reference to Figure 1, which shows the transfer label placed for the application. The label is printed on a reinforcing layer, formed by a film substrate 1 which can be any thin film, but in the case described is polypropylene 50 microns (2 mils) thick. 3 is an acrylic coating that may or may not be employed, depending on the type and source of the available film. 2 is a release material that covers the film 1. In the case of the invention this is silicone that is applied at the time of manufacture of the film. All the printed ink material is represented by the reference number 4. Depending on the graphics of the label and the opacity requirements, the ink materials can be as many as 5 different colors in one or more layers, some of them which can overlap with the others. 5 and 6 represent two (2) layers of adhesive to indicate the constitution of the adhesive from 226 g to 680 g (0.5 to 1.5 pounds) per ream, depending on the uniformity and rigidity of the labeled surface, of the container that is labeled. After application, all the printed materials are transferred from the film substrate 1 coated with the silicone release. The transfer layer is then formed by layers 3, 4, 5 and 6. The printed ink materials are urethane-based resin, vinyl or acrylic, colorable with stable pigments at temperature and ultraviolet light. In the case of white ink, titanium dioxide is the pigment of choice. The particle size ranges of the pigment are from three (3) to five (5) microns. The printed adhesive is an organic material that has water with an initial adhesion temperature of 85 ° C (185 ° F). This initial adhesion temperature is very important for the plastic labeling process because it determines the required temperature of the plastic surface at the time of transfer. In the case where the particular plastic container that is labeled is a returnable box for bottles, there is no support for the internal surface. From here, it is desired to keep the plastic of the box below 93 ° C (200 ° F) to avoid distortion of the surface when it reaches its point of deformation during the transfer of the label. Figure 2 shows a schematic side view of a box washing apparatus, for removing the transfer layers according to the present invention from the boxes 12 that are supplied to the box washer 10, via a conveyor 11. The boxes 12 they are first transported to the pre-rinse station 13 and sprayed with a pre-rinse solution which is applied from a number of nozzles 14 above and below the conveyor 11. The speed of the conveyor 11 is such that the time of residence of box 12 in the pre-rinse station is between 6 and 8 seconds. The temperature of the pre-rinse solution is 60 ° C. The pre-rinse solution preferably comprises a 0.5% sodium hydroxide solution. After passing through the pre-rinse station 13, the boxes are transported through a soaking station 15 via a downward sloping section 16 of the conveyor 11. The residence time of the box in the station Soaking is between 10 and 40 seconds. In the soaking station, the box is completely submerged and a soaking solution is recirculated in the soaking station 15 by means of the nozzles 35, to cause turbulent soaking conditions. The turbulent soaking conditions may for example include the recirculation of liquid from the soaking station 15 via the nozzles 35 at a rate of 60 m 3 / hour for a total volume of the 5 m 3 soaking solution. It is important that the transfer layers are completely removed from the boxes 12 in the soaking station 15, with no pieces remaining on the boxes. Such remnant pieces could, when dried, adhere firmly to the boxes and form an undesired contamination of the surface of the box. From the soaking station 15, the boxes are transported via the slide guide 17 of the conveyor with slope upwards, towards a post-rinse station 18. The post-rinse solution may comprise water at a temperature of 30 ° C. The residence time of the boxes in the post-rinse station 18 is between 6 and 13 seconds. Connected to the rinsing station 13, 18 and the soaking station 15 are the screening sections 20, 21 and 22. Each screening or screen section comprises a rotating band screen 23, 24, 25, "which are driven by the engines 26, 27, 28 respectively Pumps 29, 30 and 31 pull the rinse liquid and the soaking liquid from each respective station through the rotary sieve bands 23, 24, 25 at a speed of eg 60 m3 / hour The screened liquids are recirculated back to the nozzles 14 and 19 in the pre-rinse and post-rinse stations 13, 18 respectively and to the soaking station 15. Figure 3 shows a cross-sectional view throughout of lines III-III of Figure 2. It can be seen that the screen strip 24 is rotated about two rolls 37, 38. The upper end of the screen strip 24 extends above the level of the soaking liquid in the soaking station 15. The ban sieve 24 comprises a screen element in the form of a double layer web, with a mesh size of 2 millimeters. During the operation it is important to continually rotate the screen band 24 to prevent the label pieces of the transfer layers that break into pieces in the soaking station 15 from plugging the screen band. A spray nozzle 39 cleans the surface of the screen elements in the form of a strip by high pressure water or air jets. Lps removed label elements are collected in a collection bin 40. It was found that a very efficient removal of the labels from the boxes 12 is achieved by the use of a 0.5% sodium hydroxide solution in the pre-rinse station 13 in the soaking station 15. However, it is It is also possible to apply a pre-treatment material on the labels, before the entrance to the box washer 10, which acts to soften the label before the entrance to the box washer. For example, an active surface component can be sprayed onto the boxes 12 when they travel to the box washer 10. It is also possible to apply a gel-like material of a chemical composition which begins by attacking the label before entry to the box washer 10. In such a case it may be possible to use water only in the box washer 10, instead of the alkaline solution. Figure 4 shows a transfer label according to the present invention comprising a carrier, or reinforcement layer 48 formed for example by a polypropylene film of 50 microns (two thousandths of an inch) in thickness. A silicone release layer 49 is located on the carrier layer 48. On the silicone layer 49, eg, it places a transfer layer 50 consisting of a top containment layer 51, a layer c} and continuous ink 52, a lower containment layer 53 and an adhesive layer 54. After the coupling of the transfer layer 50 to a container, the carrier layer 48 and the silicone layer 49 are removed under the application of heat and pressure. The adhesive layer 54 attaches the transfer layer 50 to an underlying surface of the container, and the outward facing layer is formed by the upper containment layer 51. The carrier layer 48 of the label, which is provided with the plant silicone 49 cured by electron beam, may for example be a polypropylene film of 25.4 to 76.2 microns (1-3 thousandths of an inch) in thickness as supplied by Mobil Chemical, Films Division, Rochester, New York. Prior to the printing of the upper containment layer 51, on the silicone layer 49, the silicone surface must be treated by corona. A corona treatment will allow uniform wetting of the impression materials and allows not to damage the release of the transfer layer 50. Preferably, the corona treatment is applied to the carrier layer 48 and the silicone layer 49 shortly before it is applied. Apply the first impression of the containment layer 51. An objective treatment level should be approximately 30% of 3.5 kW. During the handling of the carrier layer 48 coated with silicone, care must be taken not to scratch the silicone layer 49. The scratching of the silicone layer 49 allows the containing layer 51 to contact and adhere to the polypropylene film 48, which could adversely accept the transfer of the transfer layer 50 during the application. The upper containment layer 51 consists for example of ink without pigment, and has several functions. First, it retards or 'prevents the penetration of water into the underlying ink layer 52. As the layer 51 is printed wider than the underlying ink layer 52 it forms part of a wrap that completely surrounds the colored ink layer 52. In addition, the upper containment layer 51 provides a consistent medium between the ink and the silicone release surface 49. Layer 51 is very important for the full transfer capacity of the label, and must be applied to a weight of at least 1.4 g / m2. It is important that after the application of the upper containment layer 51, this layer is free of air bubbles and small holes. In addition, the top containment layer must be dry before printing the subsequent ink layer 52 on it. After printing of the upper containment layer 51 on the release layer 49, an optimum release force of 10Q g or less on the press must be measured in a standard tape release test. Within five hours after application, the release force of the top containment layer will be approximately 60% smaller, or 40 g. With the specified detachment force, the containment layer 51 must be completely removed. A suitable material for the top containment layer 51 is available from Environmental Inks and Coatings, Morganton, North Carolina, under the type number 1304. Examples of a preferred ink for the ink layer 51 include an organic ink having water, available from Environmental Inks and Coatings, Morganton, North Carolina, under the type number Aqua PW EH-31721, EH 53016, EH 90967. These inks have high stability even at temperatures above 200 ° C without discoloration or loss of adhesion . the lower containment layer 53 provides a strong interface between the adhesive layer 54 and the colored ink layer 52. It is formulated to chemically anchor to the ink and provide excellent wetting and bonding of the adhesive layer. The lower containment layer 53 is attached outside the ink layer 52 to the upper containment layer 51, such that a closed envelope is formed around the ink layer 52. A suitable material for the lower containment layer 53 is available of Environmental Inks and Coatings under type number 1189. Adhesive layer 54 can be formed by an organic material having water, which is printed on a number of consecutive flexographic stations such as three stations, or can be flow coated on a unique station. The adhesive layer 54 can also be applied by a simple rotogravure printing station. Preferably, the adhesive 54 is activated by heat and has a low tack or tackiness temperature, from 80 ° C to 107 ° C. The preferred weight of the adhesive is approximately 3.5 g / m2. A suitable adhesive is available from Environmental Inks and Coatings, under type number XP 11358. The layers of the transfer layer 50 can be applied on a flexographic printing press with up to 10 stations of impression. Five stations can be used for printing the layers 51, 53, and the adhesive layer 54, which can be composed of three separate adhesive layers. Five types of colored ink 52 can be applied using the five remaining flexographic printing stations. Instead of a flexographic printing process, a rotogravure press equipped with a crown triager can also be used. Because the material coating is heavier than in the flexographic process, only three rotogravure printing stations may be necessary for the application of the containment layers 51 and 53 and the adhesive layer 54. Printing processes may also be used. by rotary stencil, additional, for the application of layers 51, 53, and 54. After 2 the impression of the lower containment layer 53, care must be taken that it extends beyond the perimeter of the ink pattern 52, but remains within the perimeter of the upper containment layer 51. It is preferable that the adhesive layer 52 extends beyond the perimeter of the lower containment layer 53 and engages the perimeter of the containment layer 51 of the highest part. In the embodiment of Figure 5, the ink layer 52, 52 'and the adhesive layer 54, 54' are discontinuous. The adhesive layer 54, 54 'is printed on the ink pattern 52, 52' such that it has a small overlap with the printed areas. Adhesive layer 54, 54 'in this embodiment is coupled to upper, continuous containment layer 51. In this way, in order to break the transfer layer 50, only the upper containment layer 51 needs to be broken, so that the soaking solution can quickly penetrate into the adhesive layer 54 and the transfer layer 50 becomes easily uncoupled. . In the embodiment of Figure 6, the adhesive layer 54 is a continuous layer. The upper containment layer 51, 51 'has been printed to register with the ink pattern 52, 52' such that it has a slight overlap with the ink areas. Again the ink pattern 52, 52 'is encased between the containment layer 51, 51' and the adhesive layer 54. The ink pattern 52, 52 'can be formed by individual letters, individual words or individual patterns such as broken lines , Squares, etc. The minimum dimension of the individual ink patterns can be as small as 0.5 mm. In the embodiment of Figure 7, a self-adhesive ink 52, 52 'has been used, which directly attaches to a surface of the container. The ink is coated by an upper, continuous containment layer 51. Finally in Figure 8, the containment layer 51, 51 'and the adhesive layer 54, 54' are discontinuous and are printed to register with a discontinuous ink pattern 52 , 52 '. Again the ink is encased in shells between the layers 51 and 54. The access to the adhesive layers 54, 54 'by the soaking solution is very good through the open areas between the pattern of the layers 51, 52, 54, 51 ', 52', 54 'and 51", 52" and 54"Figure 9 shows a schematic figure of the process of applying a transfer layer from a transfer label according to the invention to a returnable box 59. The label application process will now be described in the order of progression, Station 60 shows the surface treatment step and temperature stabilization by means of a preheat treatment using a flame heater or burner 60 '. For the adhesion of the two polymeric materials to occur, many factors must be considered such as neatness, pressure, temperature, contact time, surface roughness, movement during bonding and thickness of the p adhesive particle. An additional important consideration is the critical surface tension. The commonly accepted method of measuring critical surface tension is with a Dyne solution, which is well known. For most adhesive applications, the critical surface tension of the polyethylene is 31 x 10"5 N / cm (31 Dinas per centimeter) A series of tests were performed, which showed the best adhesive adhesion previously described, to the polyethylene surface, a treatment level of 60 x 10 ~ 5 to 70 x 10"5 N / cm (60 to 70 dynes per centimeter). The additional test of commercially available equipment showed that the flame treatment optimized the cost of capital, the cost of operation and the time required to achieve the critical surface treatment required. In order for the adhesive to achieve and maintain stickiness or adhesion quickly, it is necessary to heat the polyethylene case 59 in station 61 before the adhesive on the label is in contact therewith. To avoid deformation of the container, it is desirable not to heat the surface above 93 ° C (200 ° F). Since the surface temperature that leaves the flame treatment is about 52 ° C (125 ° F), it is necessary to heat the surface to approximately 24 ° C (75 ° F) at station 61. Here again, many options are available for heating. Hot air, additional flame heaters, gas-powered infrared panels and electric ceramic panels were all tested and found to be either too slow or difficult to control. It was found that a fused, flat, electrically heated quartz emitting plate 61 'with zone band control for localized label transfer could provide maximum free air transmission of the infrared energy without the effects of environmental factors. With an emissivity of 0.9 for polyethylene, a desired emitter plate temperature of between 900 ° C (1652 ° F) to 940 ° C (1725 ° F) will emit the most efficient wavelength (2.5 to 3.2 μm). of infrared energy for maximum absorption. The unit tested was rated at 60 watts per square inch. The time to heat the polyethylene surface as necessary, ie 24 ° C (75 ° F) was 4.5 seconds at a distance from the emitter plate of 2.5 centimeters. Station 62 illustrates the label application method by which printed ink materials are transferred from the polypropylene film substrate to the polyethylene surface using the tactile characteristics of the heat activated adhesive, to overcome the bonding of the layer Transfer to corona-treated silicone coating. The factors that influence the transfer are the contact time, the temperature and the pressure applied during the contact and the film tension during the contact, particularly the tension of the film after "the release of the ink. of the pressure roller 63 is also a factor but not a variable.For this application the diameter of the roller is 38 mm.The roller 63 is made of silicone rubber on a steel core, with the rubber durometer in the range of 50 Shore A to 80 Shore A. It should be noted that the distortion (flattening) of the rubber roller is less than a higher durometer, consequently the contact area is smaller and the transfer pressure is higher. high linear speeds where contact time is minimized, so a box that moves 18.3 meters per minute ($ 0 feet per minute) beyond a roller diameter of 38 mm will have a time of contact of 1 millisecond by 1 degree of rotation- of roller, where there is no distortion of the roller. The pressure of the roller is provided by an air cylinder 64 activated by a conventional solenoid valve which in turn is operated by two (2) switches in proximity, one to advance the roller and the other to retract it. Other means, such as mechanical union are obvious, and will not be listed here. The pressure is distributed across the length of the cylinder and for this particular label, the transfer is in the range of 12 to 17 kilograms per centimeter of roll length which is desirable. In this way, the invention. It results in the film being made, advancing at exactly the same speed as the box moving beyond the roll, under the heat activated adhesive, which adheres to the surface of the box, high energy. The pressure roller 63, which rotates freely, maintains the same tangential velocity as the linear speed of the film and the box. In this way, the ink is transferred completely and without distortion. For fast and complete adhesion purposes the pressure roller 63 is molded to a hollow core. Suspended within a hollow core is a resistance heater operated through a controller. The heating element, adjusted to 500 watts, will keep the surface of the roller at any predetermined temperature. For purposes of the invention, the surface temperature of the roll is in the range of 120 ° C to 190 ° C (250 ° F to 370 ° F).

Many polymeric films coated with silicone can be used for the printed substrate. High temperature films such as polyester can be operated in continuous contact with the hot roll. . Low temperature films such as polypropylene should be prevented from coming into contact with the hot roll during pauses in the labeling operation. To achieve this, the film guides 65 are used to support the film when the roller is retracted. The guides 65 are mounted to maintain a clear space of approximately 13 mm between the guides and the labeled surface. At the same time the roller is retracted approximately 13 mm behind the film. By maintaining these free spaces, scratching and distortion of the film such as polypropylene are avoided. The films at high temperature would not require the guides. It has also been discovered that the tension of the film, especially on the exit side of the film of the roller, is important to complete the transfer of the ink. Through tests, it was found that a continuous voltage of approximately 2.5 kilograms is useful. This is achieved through a spring-loaded floating arm, and the roller. Conventional clamping rollers and stepper motors are used to advance the film to the next label and place it precisely, using a printed mark to fire an optical scanning device. The protection of the ink against scratching by the casual handling, as well as the assurance of its resistance to environmental conditions, when subject to outdoor storage, is achieved with the application of an aqueous emulsion of wax based on acrylic, in the station 66. This is applied by a roller plunger 68 which is supplied from a wet roller with a controlled amount of coating. The control is achieved with a scraper blade. The coating extends far beyond the edges of the ink pattern and seals the edges of the intrusive moisture. The final processing step is to coalesce the layers of the coating, the ink of the label, and the adhesive in the station 67 by means of the flame heater 67 'and also to interdiffuse the adhesive layer with the polyethylene substrate formed by the box 59. This discovery was made through extensive testing of many heating systems. Since it was discovered that flame treatment is the best technique that could provide the surface energy required for label adhesion, it was found that the flame treatment of the label and the coating compound was the best technique that it could develop the durability of immersion in water, without sacrificing the mechanical properties or altering the visual characteristics of the applied label, or distorting the polypropylene case 59. To illustrate the various properties that influence the adhesion and the washing ability of the layer of preferred transfer according to the present invention, the following tests were carried out at c-abo, including a wash test, a pencil scratch test, a water uptake / release test and a vapor transmission rate test of water, as described hereinafter.

Washing Test To determine the optimal washing conditions for the labels according to the present invention, a transfer layer 50__ having the configuration as shown in Figure 4 was applied to a polyethylene box. The dimensions of the label were approximately 10. by 10 centimeters and the adhesive layer 54 was a 100% urethane adhesive with an adhesion temperature of 79 ° C. The labels were applied to the box with a roll temperature 63 in Figure 9 of 155 ° C at a roll pressure of 2.5 bar. The preheating temperature of the box (in stations 60 and 61 of Figure 9), it was 75 ° C. The speed of the boxes 59 through the label applicator was 40 boxes per minute. To determine the influence of the post-treatment temperature with which the boxes were heated after the application of the labels in station 67 of Figure 90, the post-treatment temperatures of 40 ° C, 65 ° C and 90 ° C were used. ° C. After application of the label, the boxes were stored for at least 24 hours at a temperature of 20 ° C. The boxes to which a label was applied were afterwards soaked in a 0.5% sodium hydroxide solution at temperatures of 20 ° C, 50 ° C and 70 ° C. The soaking of the boxes was carried out in a 20 liter soaking bath without turbulence, for a soaking time (10-50 seconds) such that after spraying the box soaked with a shower at a speed of 6 liters / Minute, the tag was completely eliminated within 2 seconds. ß prepared a second group of boxes where after the application of the labels, a wax coating layer was applied, as in station 6 of Figure 9. The results of the soaking times required for the removal of the labels within 2 seconds, versus the post-treatment temperature, are given in tables -I and II. From Table I, the results of which are shown graphically in Figure 10, it can be observed that for labels to which the wax layer was not applied, the soaking time drastically decreases at the temperatures of the soaking solution above 20 ° C. For post-heat treatment temperatures of 90 ° C, the durability of the label was increased and the soaking times remained above 5 seconds.

TABLE I box wash test (no wax coating applied) It was found that an optimum thermal post-treatment temperature was between 65 ° C and 90 ° C. At temperatures of thermal post-treatment above 65 ° C, very little coalescence of the applied transfer layer was achieved, such that. the transfer layers applied had insufficient durability and could be very easily removed during storage and use. At post-heat treatment temperatures greater than 90 ° C, the durability of the transfer layer became very large, and rapid removal times could not be achieved in an economically feasible manner. During the period of spraying with the spray head or shower, it was observed that after soaking, the labels were uncoupled from the box and broke into several pieces (2 to 4). When before the flame treatment step at station 67 in Figure 9, a wax layer is applied at station 66, the durability of the labels is improved, and the soaking times are increased. From Table II it can be seen that for a caustic solution at 0.5%, the wax coating leads to longer soaking times. The results of Table II are shown in graphic form in Figure 11.

Table II case washing test (with wax coating applied) It was observed that when trying to remove the labels as they were tested in the washing test described above, only with water jets at high pressure at 20 ° C and a pressure of 120 bar, at a conveyor speed of 15 meters per minute and at a spray angle of 90 ° at a distance of 10 centimeters, the removal of the label was not achieved. Even for labels without any wax coating and without thermal post-treatment, removal by means of high-pressure water jets was not possible.

Scratch Test with Pencil The purpose of the pencil scratch test is to identify the minimum or maximum durability of a label that can be obtained by taking different measurements, such as the use of a covering wax layer and heat treatment to cause the coalescence of the layers. the label. The boxes with labels that were applied with different post-heating temperatures, with and without wax, have also been tested. The labels were the same labels that were used in the washing tests described above, and were applied to the boxes under the same conditions. 4 The pencil scratch tests were carried out with a "scratch resistance tester model 435" supplied by Ericson (PO Box 720, D-5870 Hemer, Germany). During the scratch test, a pencil with a plastic insert was used to scratch the label at a 90 ° angle horizontally in the middle part of it. After application of the label, the boxes were stored for at least 24 hours at a temperature of 20 ° C. Before scratching, the boxes were soaked in water without turbulence at 20 ° C. The results of the scratch test are given in Table III and eμ Table IV in which the scratch results are given in N.

Table III scratch test with pencil (in N¡ label without wax coating) Table IV Scratch test with pencil (in N) label with wax coating i From Tables III and IV it can be seen that the post-heating flame treatment does not appear to influence the scratch resistance of the transfer layers significantly in the dry state. The durability of the transfer layer is nevertheless increased by post-heating flame treatment, as is apparent from the greater hardness of the pencil after soaking. From Table IV it appears that the application of a wax coating that covers the label, improves the scratch resistance of the dry label, significantly. It was found that for high temperatures of post-heating flame treatment of 110 ° C in combination with a wax coating, a scratch force of 8 Newtons was achieved. Labels with a hardness of 8 Newton's pencil are considered semi-permanent labels that can not be removed in an economically feasible way. Also, at post-heating temperatures above 90 ° C, problems occurred during the labeling because at these temperatures the polyethylene boxes become fragile after a few applications, it was found that the pigments in the boxes become discolored and deformations occur. the softened boxes on the conveyor and the granulator. At a post-heating temperature below 65 ° C, it was found that the resistance to labels is insufficient for labels that did not have a wax coating. For labels without a wax coating the pencil hardness, objective, in the dry state should be about 1.2 Newton and the soaking time until the df scratched force falls below 0.3 Newton, should be less than 3 minutes. For a wax-coated label, the target scratching force should be approximately 5 Newtons in the dry state, and the soaking time until the scratching force falls below 0.3 Newtons should be less than 10 minutes. It was found that the transfer layers having the above properties have an optimal combination of durability and wash capacity.

Water Capture Test The labels according to the present invention can be easily removed from a container, in particular from a plastic box due to its specific permeability in water, which allows the soaking solution to penetrate the label, and subsequently break the label into pieces and the decoupling of the container. It was found that the preferred labels have a water absorption of about 5 g / m2 after 3 hours in a water uptake test, as described below. The labels according to the invention have a water uptake value greater than 0 and less than 100 g / m2 in 3 hours. The water release of a preferred label was 4.5 g / m2 within 30 minutes in the water release test, as described below. Preferred labels according to the present invention will have a water release value greater than 0 (a complete barrier) and less than 100 g / m2 after 3 hours. Two samples were prepared > each sample containing 2 labels of a thickness of 12.7 microns each at 22.4 ° C and 48% relative humidity, each sample having a surface area of 85.8 cm2. For each sample, two labels were applied on a single piece of clear glass measuring 7.62 cm x 22.86 cm x 0.05 cm (3 inches x 9 inches x 0.02 inches). Due to the extremely low weight of the labels it was necessary to apply two labels per piece of glass to obtain a weight that could register within the range of μna electronic scale in grams of two decimals. The samples were prepared as follows: the glass supports were perfectly cleaned and placed in a heating oven until an approximate temperature of 121 ° C (250 ° F) was reached on the surface of the glass. The glass was then removed from the heating furnace and placed on a silicon rubber mesh. A label was immediately fitted on the glass and the surface was secured by the use of a silicone roller. Roller pressure was continuously applied to the full length of the label, until all trapped air was removed (approximately 5 to 6 backward and forward movements). After the glass had cooled, the carrier label was removed. After this the opposite side of the glass plates was labeled by heating a clean aluminum plate (slightly larger than the glass plate) to approximately 121 ° C (250 ° F) in a convection oven, then placing the glass on the surface of the aluminum plate (surface of the label facing down) which allowed the heating of the upper glass surface. The label was then applied and secured in place by the silicone roller as described above. Once again, when the glass cooled, the carrier film was removed. Next, a wax coating having a dry weight of 0.043 grams was applied to the surface of both labels. In the final step, using a flame of propane oxidation, flame treatment was applied to both labels by rapidly passing the flame through the entire surface of the label sample. Once the samples were cooled, the labels were ready for the water uptake test. A stainless steel immersion tank of 33.66 centimeters in diameter and 24.13 centimeters in height was filled with deionized water. Care was taken that the water level was deep enough to allow the total immersion of the sample. The sample was placed with the short dimension adjusted perpendicular to the bottom of the tank. The glass supports were placed on a thin wire frame in the immersion tank. A thermocouple was installed inside the water immersion tank. After each period of time, as given in Table V, the sample was removed from the tank, the excess surface water was air dried, the sample was weighed and placed back in the tank. This procedure was continued for the duration of the test. The results are shown in Table V. With respect to sample 1, this sample reached its maximum absorption of 0.04 grams at the 3-hour mark, and maintained its level at the 5-hour mark before exhausting its ability to retain water. at this level. After the 5 hour period, the label lost its ability to retain water. It is believed that this phenomenon was caused due to the structural degradation of the label. For sample 2, this sample also reached its maximum absorption of 0.04 grams at a 3-hour mark. At the 5 hour mark this sample was finished to be tested in the preparation for the water release test described below. From the water uptake test, it can be deduced that a preferred level of a thickness of 12.7 microns has a water uptake value of 0.04 g / 85.8 cm2 or about 5 g / m2 after 3 hours at room temperature.

Table V Water Capture Test In order to calculate the weights in grams of the individual labels from the data in Table V, reference is made to the following: Each sample incorporated the use of two labels. To calculate the weight of Sample 1 at 1:00 p.m., subtract the reading from 8:00 a.m. of reading at 1:00 p.m. and divide by 2 As in the example: reading at 1.00 p.m. 59.85 reading at 8 a.m. 59.77 0.08 / 2 = 0.04 grams Water Release Test Immediately after the conclusion of the previous Water Capture Test, Sample 2 as prepared above was subjected to the water release test. The sample was air dried to remove excess water, weighed and the data recorded. The sample was first exposed to room temperature for half an hour and weighed. Half an hour after weighing the sample, it was placed in a preheated test oven (53 ° C) (small electrically heated oven, Quieny Lab Inc., Model 20 laboratory oven or equivalent). The sample was left in the preheated oven for more than an hour and weighed. After this the sample was placed back in the test oven and remained there for 3.5 hours. From Table VI it can be concluded that the water absorbed by sample 2 was released within 30 minutes of exposure to ambient temperature and ambient humidity (48%). In fact, the sample registered a weight loss of 0.01 grams from its original weight, which might seem to indicate that the label was not perfectly dried in the installation. Thus, a preferred label of size 85.8 cm2 and 12.7 microns thick has water release greater than 0 and less than 0.10 g / 24 hours with an average release of 0.045 g within 30 minutes, given these parameters.

Table VI Water Release Test Water Vapor Transmission Rate Test The optimum combination of durability and washing ability of the label according to the invention is at least partly due to the permeability of the label for the soaking solution. A sample of the transfer layer of the same type as tested in the water capture / release test with a thickness of 12.7 microns was tested for water vapor transmission. A 25 milliliter glass container with a circular hole of 15.9 millimeters diameter was cleaned with acetone and filled with approximately 10 milliliters of deionized water. The area of the orifice of the vessel was heated to approximately 47.8 ° C (118 ° F) and a circle segment of the transfer layer was firmly applied using a small piece of silicone rubber as a pressure pad. After the container / label had cooled, the reinforcing film was gently removed. The sample preparation was completed by the addition of a wax coating (0.001 g across the 1.99 cm2 surface) and allowed to air dry. A second glass container of the same dimensions as described above was thoroughly cleaned with acetone and filled with 10 milliliters of deionized water. The orifice area of the sample was also heated. This sample was used as a control sample. The completed samples were then weighed at various intervals in a time period of 26.6 hours. The speed of transmission of water vapor over the total time of the experiment equaled 568.75 g / m2 in a period of time from 24 hours at 22.2 ° C to 46% relative humidity. It was found that a water vapor transmission rate "in the idle state" was not achieved until approximately 28 minutes from time 0. When the "rest" state data are used after 28 minutes from time 0, it was found that the water vapor transmission rate is approximately 526.93 g / m2 in 24 hours.For the control sample without a label, a water vapor transmission rate was found in the total experiment time of 1085.7 g / m2 in 24 hours The water vapor transmission rate of the preferred label according to the present invention will fall between 50 g / m2 and 750 g / m2 after 24 hours (22.2 ° C, 44% relative humidity), preferably around 500 g / m2 after 24 hours.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (23)

1. A transfer label, comprising a reinforcing layer and a transfer layer releasably coupled thereto. whose transfer layer can be uncoupled from the reinforcing layer for transfer to a container, the transfer layer comprises an ink pattern, characterized in that the transfer layer, after coupling to a container and under turbulent soaking conditions in an aqueous liquid of a temperature of not more than 100 ° C, preferably not greater than 70 ° C, breaks into at least 4 parts, each part not smaller than 5 micrometers and is uncoupled from the container within a time of soaking no more than 20 minutes, preferably no more than 10 seconds.

2. The transfer label according to claim 1, characterized in that the transfer layer is permeable for the soaking liquid.

3. The transfer layer according to claim 1, characterized in that the layer 5 The transfer layer comprises a cover layer superimposed on the ink pattern, the cover layer forming the outward facing layer after the coupling of the transfer layer to a container, wherein the cover layer is permeable for the soaking liquid.

4. The transfer label according to claim 1 or 2, characterized in that the ink pattern is discontinuous, such that areas of reduced thickness are formed in the transfer layer.

5. The label according to claim 3 or 4, characterized in that the cover layer is discontinuous and covers the discontinuous ink pattern.

6. The transfer label according to any of the previous claims, characterized in that the transfer layer comprises a layer of adhesive, the adhesion or tackiness of which is at least reduced by contact with the soaking liquid, preferably being dissolved in the soak liquid. "

7. The transfer label according to claim 6, characterized in that the adhesive layer is discontinuous.

8. The transfer label according to claims 4 and 7, characterized in that the adhesive layer is located in register with the ink pattern.

9. The transfer label according to any of the previous claims, characterized in that the soaking solution is an aqueous alkaline solution.

10. The transfer label according to any of the previous claims, characterized in that it has a thickness of less than 30 micrometers, preferably between 5 and 20 micrometers.

11. The transfer label according to any of the previous claims, characterized in that it comprises an adhesive layer of a weight between 1 and 10 g / m2, preferably between 3 and 7 g / m2.

12. The transfer label according to any of the previous claims, characterized in that the adhesive layer comprises at least two sublayers, the tack or adhesion of the sublayer which after coupling to a container is closer to it, has a tackiness or adhesion less than the adhesive layer located farther from the container.

13. A container, in particular a plastic box, characterized in that it comprises a transfer layer that has been applied using a transfer label according to any of the preceding claims.

14. The container according to claim 13, characterized in that the covering layer comprises an acrylic wax.

15. The container in accordance with any of. claims 13 or 14, characterized in that the cover layer is joined at the moment after the coupling of the transfer layer to the container.

16. The container according to any of claims 13, 14 or 15, characterized in that the transfer layer has been heat treated after application to the container, at a temperature between 40 ° C and 100 ° C, preferably between 50 ° C and 90 ° C.

17. The container according to any of claims 13 to 16, characterized in that it comprises an application surface for the transfer layer, whose application surface before application, has a surface tension of at least 60 x 10"5 N / cm (60 Dinas per cm).

18. The container according to any of claims 13 to 17, characterized in that the label on the container has a pencil hardness between IN and 7N in its dry state, and a pencil hardness less than 0.5 N after a soaking time between 1 and 15 minutes in water as a soaking solution at 20 ° C.

19. The container according to any of claims 13 to 18, characterized in that the label on the container has a water capture value after 3 hours greater than 0 and less than 100 g / cm2, preferably approximately 5 g / cm2. .

20. A method for washing a container according to any of claims 13 to 18, characterized in that it comprises the steps of: a. placing the container in an aqueous soaking solution during a soaking time of not more than 20 minutes, preferably not more than 1 minute, the temperature of the soaking solution is lower than 100 ° C, preferably lower than 70 ° C, while turbulence is caused in the soaking solution such that the label breaks in at least 4 parts, each part not smaller than 5 micrometers and is uncoupled from the container, pumping the soaking solution through a sieve and collecting the pieces of the label by the sieve, cleaning periodically, preferably continuously, the sieve by collecting and removing the pieces of the label.

21. The method according to claim 20, characterized in that the size of the screen openings is between 1 mm and 10 mm, preferably about 2 mm.

22. The method according to claim 20 or 21, characterized in that it comprises the step of crashing jets of water on the container before and / or after placing the container in the soaking solution.

23. The method according to claim 20, 21 or 22, characterized in that the soaking solution comprises a NaOH solution comprising between 0.1 and 5% by weight, preferably approximately 0.5% of NaOH.